Mauricio Mena

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since Apr 14, 2013
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Recent posts by Mauricio Mena

I was reading the table of content for the book and I just found a entire chapter talking about KTable, I never heard about it before, but sounds to me pretty similar to the KQSL tool that confluent provide. It was hard to found resources about the KTable to understand the difference, could you please help me to understand if there is any difference, or if both technologies work together and where I can found more resources about KTable.
Also a question about KTable, is if it will possible to create one from an existing topic and just query it later ?.  What about if I am just interesting in the metadata not the body of the message?

Thanks and congratulations for your book.
First of all, congratulation for the book.

I have a question about the usage of kubernetes within AWS, I read through the summary of the chapters of the book and I don't see anything related to cloud deployment, also I hear that Amazon created new service that uses Kubernetes (Amazon Elastic Container Service for Kubernetes (Amazon EKS)), reading your book and the concepts that I believe should be there, how feasible is that will understand better what I will see in the cloud, does that will be very different ?

Also, if I don't want to use the new AWS service by itself but I want to use kubernetes on a different cloud provider your book will help me to understand how I can achieve it, without giving specifics about cloud providers?


This book is for a specific android version or at least we will have to use certain SDK version to follow all the examples ?.
Seems that the book is guiding us to create an android application, this explain a little bit how to setup your android development environment as well, as I notice some books that omits this completely and could be challenging for beginners to follow.
What about networking does this explain how get or push some data to the web. Definitively what I like for the index section is the `Staying in the background` seems really well describe how you manage this topic.

Thanks and congratulations for the new book.
1 year ago
Hi Ken Kousen. First of all, congratulation for the book, seems to be very interesting.

Nowadays people are working more often with streams, but what about the performance implications, sometimes I heard that use a for-loop has better performance (memory and speed) than use streams, there are some useful guidelines to know when use stream and when avoid them that you could share?
1 year ago
Yes thanks. I have the Java 6 certification and I would like to get the new Java 8 programmer which is my target
I have the OCJP6.0 normally I can see in the forums what are the most difficult and important topics that exam will test. From you expertise and point of view what are the most important topics that people should master in order to pass the exam. Also what would you said is the more tricky or difficult topic in the exam in which we need to pay a lot of attention.

Do you explain about the format of the exam in your book, for example in Java6 was a style of "Select 2 of 4", not sure if this exam will have the format "Select all that apply" ?

I see that there is a difference id for the exam for people that want to upgrade from java6 certification, any tips or recommendation coming from this path.

+1 I like the scenarios in which you recommend the use of an API gateway, indeed that is a great use case suggestion, thanks for clarifying when to use it. And for pointing me to the step functions which I would like to check in a near future. Thanks.
2 years ago
What to know more about the importance of having an API Gateway when you are running serverless architecture, is a requirement to manage the functions you have, it is a pattern, best practice or we are allowed to not have one in our system.
What are other ways or organize or even orchestrate our service layer running AWS Lambda?

How we can manage the inventory for our existing functions in AWS there are preexisting tools or just amazon console?
2 years ago
Yes, actually I was most interested in the concept, techniques which seem that are going to find in the book. About tools, I agree with you that changes very quickly and thanks for the link I will be very helpful.

Hi. First of all congratulation for this book, seems to be promising a lot of good topics according to the table of contents.
My question is about the debugging area, does your book have recommendations about how to debug code or offers some tips once you apply those javascript concepts, that could help the developer not only to develop ninja code, also allow them to debug it and why not troubleshoot existing code?  I see appendix B have a section, but this will be as best practices or recommended tips ?

Totally agree with you try to cover an specific cloud solution, will be not really useful for other user that are working with another one. Also interesting the way in which the book seems to be structured as cover in the points that you mention "running docker in production" also the "securing docker" the realities that you would face once you try to put this on production. Thanks for the answer .
3 years ago
I read the contents of the book and I found a very interesting section about the container orchestration about managing multiple docker containers, my question is if this section could provide the principles/basis in which the deployment of the docker containers works in the cloud, or is any other specific section that cover the cloud scenarios.

3 years ago
Hi Guys.

Today I pass the 1Z0-897 exam and my overall opinion is this test is more theoretical, there are minimum code snippets there. If you are expecting questions like "what is the correct attribute of a specific annotation" you are far from the truth. I really expect from Oracle better definition on the exam topics, some of them are unclear and just thanks to previous experience I studied some topics that I didn't consider in the beginning of the preparation. Ok let´s start from the scratch

What I did to be prepare for this exam:
1. Read completely: “Java Web Services : Up and Running” by Martin Kalin. I download the code play with some of the examples; learn some ways to create service that I did not know. To be honest I don’t like this book much, I believe is not well organize and example that involve external agents are really confused, also the part of web services security is NOT oriented to the exam type of questions (SSL config, trustore, SSL client are not in the exam really cool to know but not for pass the exam).

2. Read completely : “The Java API for XML-Based Web Services (JAX-WS) 2.2“, Take special care with chapters 4,5,6,7,9, 10, I think chapter 2,3 are very larger and there are a lot of details that are not really cover in the exam, I recommend read them try to learn what the conformance section said. (I did not see any Fault section question, not mapping or even the annotations @FaultAction so don’t expend much on it). Be sure to know the definitions of each of the WSDL sections.

3. Read completely: “JSR-311 JAX-RS. The Java API for RESTful Web Services” but important chapters are: 2,3,5,6. Here my advice is learn about the basics annotations like @Path, @Get, avoid to memorize the interfaces for Providers, Filter or Interceptors, I believe know all of them is enough but name of classes and interfaces are not needed.

4. Use this questions to learn some details, really good quiz there, be sure to take them with calm and learn by heart, Endpoint API is not really covered by the exam, but here you will have your first contact with JAXB and JAXP, so read those sections carefully because a lot of questions about different JAXP technologies come in the exam ( more theory questions not of the use of the API’s, are more related when you should use each of them)

5. Read from the beginning to the end all the chapters in, be sure to understand the real security mechanism that JAXS-WS can implement, (SAML, XACML, STS… check all of them and at least learn it definition), signatures are very important in the exam and understand completely the use of them.

6. Read about EJB and JAX-RS this is really needed for the exam, I don’t have reference in my hand about it but I recall I used Ethuware references for understand more about the topic. Be sure to learn which are the allowed implementation when use Stateless and Singleton and which annotations apply to them.

7. Finally I end my preparation with the Ethuware mock exams, although they are really useful I believe the quality and the difficulty of them are not very close to the real exam, some of the questions are repeated several times or are really easy, so don’t use this as your only guide.

My advice is be prepare for a theoretical exam, be prepare for WS-I question there are a LOT of them in the exam, learn Basic Profile v1.1 (really guys learn this stuff) understand it by heart all the allowed and not allowed things, learn the concept on them.
Expect some question about SAAJ so recommend to read the entire API it is not to long so learn by memory, be sure the name of the methods, interfaces and classes, expect easy but tricky questions on it. Also read URLConnection API and really burn in your memory both of them.
Learn security technologies and when it applies, WS-Addressing and the WDSL that is being created when you use it, MTOM and MIME is a topic short but please don’t fail any of this.

For myself I don’t take so much in consideration Basic Profile v1.1, WS-Interoperability, SOAP encoding, so I failled terrible on those questions I believe those questions are covered under the topic (Apply best practices to design and implement web services) and the exam comes with 12 question is the bigger section on the exam.

I hope this help you to clear the exam with good score.

Good luck Web Services Developers. =)

Hi All.

Sometime ago I came here to obtain some guidance about what are useful resources, guide and topics that I should study looking for pass 1Z0-898 exam. I would like to share my experience as I think this will be helpful for other people preparing to takes this exam.

1. Absolutely read and fully understand the Pro JPA 2: Mastering the Java™ Persistence API, Mike Keith (Author), Merrick Schincariol (Author) this book is a must, read once to gain full knowledge about the concepts and then return to the part that you need to read with more detail.
2. This exam I think will be passed with great score reading and fully understand the specs. JSR 317: JavaTM Persistence API, Version 2.0, consider this after read the first book because the description of the topics are not very well but give to you a lot of statements that will appear in the exam.
3. This is not commonly said but JSR 318: Enterprise JavaBeansTM,Version 3.1EJB chapters 13 and 14 need to be read and fully understood, also good knowledge in EJB basics are welcome for this exam, you will see question in the exam talking about java.rmi.RemoteException, javax.ejb.EJBException, a lot of question that reference to stateful, stateless. I don't see nothing about MDB but consider read the section as well.
4. Answering question in StackOverflow this will give me a lot of real experience in how apply the knowledge that I learned and put me in the top answerer of the month =), before a guy that is really amazing in the jpa knowledge.

I take two months and a half preparing for this exam, more or less 1 or 2 hours per day, some exercises about CriteriaQuery, JPQL and mappings . I have a good ones that I planned to put in github later.

5. Finally after you think you will be ready for the exam, takes ethuware exams are very closed to the real exam and prepare you for a kind of tricky details that you need to be aware.

Be prepare for a lot of question of JPQL and Criteria, be prepare for really memorize Cache stuff, transactions (CMT, BMT) and a lot of questions about EM and Persistence Context, memorize the PersistenceException and its sub classes be sure to know what make tx marked for rollback. Take in mind that Locking is a topic with several question. Study very well AssociationOverride and AttributeOverride this is a must.

I think this exam is more light than Web Component but don't rely on.

So, that was my advice good luck ....